Purpose <p>The current guidelines recommend cisplatin-based adjuvant chemotherapy for patients with completely resected stage II-III non–small cell lung cancer (NSCLC). Carboplatin-based chemotherapy is occasionally selected, although there is limited evidence of its long-term outcomes. We conducted this study to compare the long-term outcomes of cisplatin- based chemotherapy with those of carboplatin-based chemotherapy.</p> Methods <p>A retrospective chart review was performed to identify patients aged ≥ 18 years with performance status 0–1, complete resection, and pathological stage II–IIIA NSCLC (7th edition) between 2014 and 2016 in our multi-institutional database. Patients were classified into two groups: the cisplatin-based adjuvant chemotherapy group and the carboplatin-based adjuvant chemotherapy group. To adjust for baseline differences, inverse probability of treatment weighting (IPTW) based on propensity scores was applied. The primary outcome was recurrence-free survival (RFS) and the secondary outcomes were cancer-specific survival (CSS) and overall survival (OS).</p> Results <p>A total 342 patients were included, of whom 195 received cisplatin-based adjuvant chemotherapy and 147 received carboplatin-based chemotherapy. After IPTW adjustment, the hazard ratios for RFS, CSS, and OS were 1.10 (95% confidence interval [CI]: 0.82–1.49, <i>p</i> = 0.526), 1.11 (95% CI: 0.68–1.82, <i>p</i> = 0.675), and 1.46 (95% CI: 0.96–2.22, <i>p</i> = 0.08), respectively.</p> Conclusions <p>Carboplatin-based adjuvant chemotherapy may be considered for selected patients deemed unfit to receive cisplatin.</p>